This invention generally relates to a flushometer for use in a urinal, water closet, or the like. More particularly, the invention relates to an improved piston-type flushometer valve.
Various types of piston-type flushometers are known in the art, as exemplified by the flush valve shown in U.S. Pat. No. 5,881,993. Another type of piston-type flushometer is taught, for example, in U.S. Pat. No. 6,913,239, which includes a domed inner cover defining the top of a control chamber. The teachings of these patents are hereby incorporated herein by reference.
Typically flushometers include a valve (piston or diaphragm) which seals the water inlet from the outlet of the valve body. The valve is controlled, at least in part, by utilizing pressure differentials, with a control chamber located within the valve body at its upper most interior. The control chamber functions to control the reseating of the valve upon the valve seat. An auxiliary valve controllably seals the control chamber from the outlet and bypasses provide metered control flow from the inlet to the control chamber. Thus, the control chamber can be pressurized to the pressure of the inlet via communication through the bypasses. As the line pressure in the control chamber acts on a larger topside area of the piston or diaphragm than the inlet line pressure acts on smaller underside area of the piston or diaphragm, the valve remains closed under equal pressures in a steady state condition. When the auxiliary valve is opened, the control chamber becomes exposed to a lower pressure i.e., smaller force, and the contents of the control chamber are vented into the outlet reducing the downward force exerted on the piston and allowing it to raise off the main seat creating an opening so that water from the inlet may flow to the outlet. The water flows over the main piston seat. The control chamber is repressurized via the bypass(s) and the valve closes as the force in the control chamber on the piston top increases past the force pushing on the underside of the piston body.
Prior piston-type flushometers experience numerous forces that result in imprecise or inaccurate flush volumes or undesirable flush profiles. For example, an air pocket may develop in the upper pressure chamber. Further, the piston, as it is reseating on the main valve seat during a flush cycle, experiences forces from the exhausting water that resist proper seating of the piston on the valve seat.